1. Field of the Invention
The present invention relates to a cooling system of a battery which cools a battery, which supplies electric power to a drive-use electric motor, by utilizing a refrigerant of an air-conditioning system which is mounted in the vehicle. A vehicle which mounts a drive-use electric motor is either an electric vehicle or a hybrid vehicle. The present invention relates to a cooling system of a battery which is designed to not detract from the comfortable feeling of air-conditioning given to the passengers by the air-conditioning system.
2. Description of the Related Art
In recent years, electric vehicles (EV) and hybrid vehicles (HV) have been commercialized. Along with this, the capacity of the batteries which supply electricity to the drive-use motors which are mounted in these vehicles has become larger and the output voltage has become higher. Further, an HV or EV carries a large number of batteries for use as sources of drive power, so the battery performance is important. To enable the batteries to exhibit their performance in full, it is important to hold the battery temperature at a suitable level.
On the other hand, in an HV or an EV, heat is generated at the time of charging the battery. In such a case, sometimes the battery becomes high in temperature. To secure the battery performance, the battery has to be cooled. For cooling the battery of a vehicle powered by a conventional internal combustion engine, air cooling by the natural flow of air was sufficient, but for cooling a high voltage battery with a voltage of 12V or higher which is mounted in an HV or an EV, air cooling by the natural flow of air is not sufficient.
Therefore, a battery cooling system which uses a refrigeration cycle of a vehicular air-conditioning system in an HV or EV so as to efficiently cool the battery is disclosed in Japanese Patent Publication (A) No. 2001-105843. In the battery cooling system which is disclosed in Japanese Patent Publication (A) No. 2001-105843, a battery cooler which is comprised of a base and a plurality of heat conduction fins is prepared, the battery is placed between two heat conduction fins, and the refrigerant which is used in the refrigeration cycle of the air-conditioning system is branched off and run to a refrigerant passage which is provided inside of the base so as to thereby cool the battery.
However, in the battery cooling system which is disclosed in Japanese Patent Publication (A) No. 2001-105843, while the refrigerant which is used in the refrigeration cycle of the air-conditioning system is being run to the battery cooler, the refrigerant is not being run to the air-conditioning system side. For this reason, in the battery cooling system which is disclosed in Japanese Patent Publication (A) No. 2001-105843, there was the problem that the cooling capacity of the air-conditioning system ended up falling at the time of cooling the battery and the venting temperature of the cooling air to the passenger compartment from the air-conditioning system ended up rising.